Isolation of L. monocytogenes from raw milk in farm bulk tank represents a serious technological and economic problem to the farmers. Due to health reasons, the use of contaminated milk is strongly limited. Therefore, the source of contamination should be reliably detected as soon as possible. In large herds of dairy cattle, examination of individual milk samples (in the first step) is almost impossible. Thus, it is necessary to prepare the pool samples. In this paper, we present a case of contaminated farm bulk tank containing milk of 85 cows. L. monocytogenes was isolated from 25 ml of sample. In the first phase of the examination, milk samples from pools of five cows were tested and L. monocytogenes was found in one pool. Further examination of individual samples within the positive pool revealed the presence of L. monocytogenes in one udder quarter of one cow. The infected cow showed no clinical signs of mastitis, but the somatic cell count was increased. Due to late gestation, the cow was dried off. After calving, the cow showed a persistent infection and was still the carrier of L. monocytogenes. For that reason, it was removed from the herd. We have found that milk from the cow with subclinical mastitis of one udder quarter was the source of contamination for the entire bulk tank. Pooling of the samples does not affect the reliability of the examination, but can considerably reduce costs.
B.06 Other
COBISS.SI-ID: 3457658Of particular concern are the so-called ready-to-eat foods with long shelf-life. L. monocytogenes is often isolated from thermally untreated meat products and also in thermally treated which are subsequent contaminated. In samples of ready-to-eat products L. monocytogenes should be absent in 5 unites of the sample when the product is at food business operator and also on the market when the L. monocytogenes shelf-life study was not performed. For 100 samples of meat products, we conducted a parallel examination of five units and combined one. At 4 samples we also determine the level of contamination and water activity. We isolated L. monocytogenes out of 25 samples. At 24 samples we managed to isolate L. monocytogenes out of at least one unit. At those samples L. monocytogenes was isolated in 16 cases out of combined sample too. We isolated L. monocytogenes out of one combined sample but not out of five unites. The level of contamination at examined samples was low and not exceeded 100 cfu/g.
B.06 Other
COBISS.SI-ID: 3444090The most commonly method used for demonstrating microorganisms in the air are sedimentation, pumping air through a liquid medium, impaction on solid medium, using Andersen sampler, and others methods. These methods have some shortcomings that affect the accuracy of the microorganisms in the air. We used the air sampler which sampling air directly into a liquid medium, using the principle of centrifugal force. In the experiment we used the method of impaction the sampler Merck, pumping through the liquid medium and sampling the air using centrifugal force in a liquid medium. The results are part of extensive research, which has not completed yet. Results obtained so far indicate a more reliable demonstration of microorganisms from the air directly into the liquid medium. During the course of research using this method we can prove the presence of L. inocua and L. monocytogenes in the air of meat plants, where could not be demonstrated by using other sampling methods.
B.03 Paper at an international scientific conference
COBISS.SI-ID: 3378298